DATASHEET
MK2705
AUDIO CLOCK SOURCE
Description
Features
The MK2705 provides synchronous clock generation for
audio sampling clock rates derived from an MPEG stream,
or can be used as a standalone clock source with a 27 MHz
crystal. The device uses the latest PLL technology to
provide good phase noise and long term jitter
characteristics in a small 8-pin package.
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Contact IDT if you have a requirement for an input and
output frequency not included in this document.
Packaged in 8-pin (150 mil wide) SOIC
Clock or crystal input
Low phase noise
Low jitter
Exact (0 ppm) multiplication ratios
Independent output voltage
Support for 256 times sampling rate
NOTE: EOL for non-green parts to occur on 5/13/10
per PDN U-09-01
Block Diagram
VDD
S0
S1
PLL Clock
Synthesis
and Control
Circuitry
X1/REFIN
27 MHz crystal
or clock input
Crystal
Oscillator
CLK
X2
Optional crystal load capacitors
IDT™ AUDIO CLOCK SOURCE
VDDO
GND
1
MK2705
REV D 122109
MK2705
AUDIO CLOCK SOURCE
CLOCK SYNTHESIZER
Pin Assignment
Output Clock Selection Table
S1
S0
Input
Frequency
(MHz)
Output
Frequency
(MHz)
X1/ REFI N
1
8
X2
VDD
2
7
VDDO
0
0
27
8.192
S0
3
6
S1
0
1
27
11.2896
GND
4
5
CLK
1
0
27
12.288
1
1
27
24.576
8-pin SOIC
Pin Descriptions
Pin
Number
Pin
Name
Pin
Type
1
X1/REFIN
Input
Connect this pin to a 27 MHz crystal or clock input
2
VDD
Power
Power supply for crystal oscillator and PLL.
3
S0
Input
Output frequency selection. Determines output frequency per table above. On-chip pull-up.
4
GND
Power
Connect to ground.
5
CLK
Output
6
S1
Input
Output frequency selection. Determines output frequency per table above. On-chip pull-up.
7
VDDO
Power
Power supply for output stage.
8
X2
Input
Connect this pin to a 27 MHz crystal. Leave open if using a clock input.
IDT™ AUDIO CLOCK SOURCE
Pin Description
Clock output.
2
MK2705
REV D 122109
MK2705
AUDIO CLOCK SOURCE
CLOCK SYNTHESIZER
Application Information
Series Termination Resistor
use very short PCB traces (and no vias) been the crystal
and device.
Clock output traces should use series termination. To series
terminate a 50Ω trace (a commonly used trace impedance),
place a 33Ω resistor in series with the clock line and as close
to the clock output pin as possible. The nominal impedance
of the clock output is 20Ω.
The value of the load capacitors can be roughly determined
by the formula C = 2(CL - 6) where C is the load capacitor
connected to X1 and X2, and CL is the specified value of the
load capacitance for the crystal. A typical crystal CL is 18 pF,
so C = 2(18 - 6) = 24 pF. Because these capacitors adjust
the stray capacitance of the PCB, check the output
frequency using your final layout to see if the value of C
should be changed.
Decoupling Capacitors
As with any high-performance mixed-signal IC, the MK2705
must be isolated from system power supply noise to perform
optimally.
PCB Layout Recommendations
Decoupling capacitors of 0.01µF must be connected
between each VDD and the PCB ground plane. To further
guard against interfering system supply noise, the MK2705
should use one common connection to the PCB power
plane as shown in the diagram on the next page. The ferrite
bead and bulk capacitor help reduce lower frequency noise
in the supply that can lead to output clock phase modulation.
Observe the following guidelines for optimum device
performance and lowest output phase noise:
1) Each 0.01µF decoupling capacitor should be mounted on
the component side of the board as close to the VDD pin as
possible. No vias should be used between decoupling
capacitor and VDD pin. The PCB trace to VDD pin should
be kept as short as possible, as should the PCB trace to the
ground via. Distance of the ferrite bead and bulk decoupling
from the device is less critical.
Recommended Power Supply Connection for
Optimal Device Performance
Connection to 3.3 V
Power Plane
Ferrite
Bead
VDD Pin
2) The external crystal should be mounted next to the device
with short traces. The X1 and X2 traces should not be
routed next to each other with minimum spaces, instead
they should be separated and away from other traces.
VDD Pin
Bulk Decoupling Capacitor
(such as 1 F Tantalum)
3) To minimize EMI and obtain the best signal integrity, the
33Ω series termination resistor should be placed close to
the clock output.
0.01 F Decoupling Capacitors
Both VDD pins must be connected to the same voltage.
4) An optimum layout is one with all components on the
same side of the board, minimizing vias through other signal
layers (the ferrite bead and bulk decoupling capacitor can be
mounted on the back). Other signal traces should be routed
away from the MK2705. This includes signal traces just
underneath the device, or on layers adjacent to the ground
plane layer used by the device.
Crystal Load Capacitors
If a crystal is used, the device crystal connections should
include pads for capacitors from X1 to ground and from X2
to ground. These capacitors are used to adjust the stray
capacitance of the board to match the nominally required
crystal load capacitance. To reduce possible noise pickup,
IDT™ AUDIO CLOCK SOURCE
3
MK2705
REV D 122109
MK2705
AUDIO CLOCK SOURCE
CLOCK SYNTHESIZER
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK2705. These ratings, which are
standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at these
or any other conditions above those indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical
parameters are guaranteed only over the recommended operating temperature range.
Item
Rating
Supply Voltage, VDD
4.5 V
All Inputs and Outputs
-0.5 V to VDD+0.5 V
Ambient Operating Temperature
0 to +70° C
Storage Temperature
-65 to +150° C
Junction Temperature
175° C
Soldering Temperature
260° C
Recommended Operation Conditions
Parameter
Min.
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Typ.
Max.
Units
0
+70
°C
+3.0
+3.6
V
DC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±10%, Ambient Temperature 0 to +70° C
Parameter
Operating Voltage
Symbol
Conditions
Min.
Typ.
Max.
Units
VDD
3.0
3.6
V
VDD
V
VDDO
1.8
Input High Voltage
VIH
2
Input Low Voltage
VIL
Output High Voltage
VOH
IOH = -4 mA
VDD-0.4
V
Output High Voltage
VOH
IOH = -20 mA
2.4
V
Output Low Voltage
VOL
IOL = 20 mA
Supply Current
IDD
No Load
24
mA
Short Circuit Current
IOS
Each output
±65
mA
Nominal Output Impedance
CIN
Internal pull-up resistor value
RPU
IDT™ AUDIO CLOCK SOURCE
0.8
ZOUT
Input Capacitance
V
Input pins
4
0.4
V
V
20
Ω
7
pF
120
kΩ
MK2705
REV D 122109
MK2705
AUDIO CLOCK SOURCE
CLOCK SYNTHESIZER
AC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±10%, Ambient Temperature 0 to +70° C
Parameter
Symbol
Conditions
Min.
Input frequency
Typ.
Max.
27
Output duty cycle
tOD
VDD/2, Note 1
Output clock rise time
tOR
20% to 80%, Note 1
Output clock fall time
tOF
45
49 to 51
80% to 20%, Note 1
Units
MHz
55
%
1.5
ns
1.5
ns
Jitter, short term
peak to peak, Note 1
175
ps
Jitter, long term
10 us delay
peak to peak, Note 1
300
ps
0
ppm
-110
dBc
Frequency synthesis error
Single sideband phase noise
10 kHz offset
Note 1: Measured with 15 pF load
IDT™ AUDIO CLOCK SOURCE
5
MK2705
REV D 122109
MK2705
AUDIO CLOCK SOURCE
CLOCK SYNTHESIZER
Package Outline and Package Dimensions (8-pin SOIC, 150 mil Body)
Package dimensions are kept current with JEDEC Publication No. 95
Millimeters
Inches
8
Symbol
E
A
A1
B
C
D
E
e
H
h
L
α
H
INDEX
AREA
1 2
D
Min
Max
1.35
1.75
0.10
0.25
0.33
0.51
0.19
0.25
4.80
5.00
3.80
4.00
1.27 BASIC
5.80
6.20
0.25
0.50
0.40
1.27
0°
8°
A
Min
Max
.0532
.0688
.0040
.0098
.013
.020
.0075
.0098
.1890
.1968
.1497
.1574
0.050 BASIC
.2284
.2440
.010
.020
.016
.050
0°
8°
h x 45
A1
C
-Ce
B
SEATING
PLANE
L
.10 (.004)
C
Ordering Information
Part / Order Number
Marking
Shipping packaging
Package
Temperature
MK2705S
MK2705S
Tubes
8-pin SOIC
0 to +70° C
MK2705STR
MK2705S
Tape and Reel
8-pin SOIC
0 to +70° C
MK2705SLF
MK2705SL
Tubes
8-pin SOIC
0 to +70° C
MK2705SLFTR
MK2705SL
Tape and Reel
8-pin SOIC
0 to +70° C
*NOTE: EOL for non-green parts to occur on 5/13/10 per PDN U-09-01
While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology (IDT) assumes
no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would result from its use. No
other circuits, patents, or licenses are implied. This product is intended for use in normal commercial applications. Any other applications
such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements are not
recommended without additional processing by IDT. IDT reserves the right to change any circuitry or specifications without notice. IDT
does not authorize or warrant any IDT product for use in life support devices or critical medical instruments.
IDT™ AUDIO CLOCK SOURCE
6
MK2705
REV D 122109
MK2705
AUDIO CLOCK SOURCE
CLOCK SYNTHESIZER
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For Tech Support
800-345-7015
408-284-8200
Fax: 408-284-2775
www.idt.com/go/clockhelp
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Integrated Device Technology, Inc.
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© 2006 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. IDT and the IDT logo are trademarks of Integrated Device
Technology, Inc. Accelerated Thinking is a service mark of Integrated Device Technology, Inc. All other brands, product names and marks are or may be trademarks or registered
trademarks used to identify products or services of their respective owners.
Printed in USA
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